1. Field of the Invention
The present invention relates to a water reuse method for removing a surfactant from for-treatment water (hereinafter “water to be treated” will be referred to as “for-treatment water”) such as surfactant-including cleaning water and rinse water to reuse the treated for-treatment water in a cleaning device such as a washing machine, and it also relates to a washing machine.
2. Description of the Related Art
Heretofore, in a washing machine for use in washing clothes and the like, city water is received in a drum, a detergent is added to form cleaning water, and a cleaning operation of the clothes and the like is executed. In this cleaning operation, a surface tension of water is reduced with a surfactant included in the detergent, and the cleaning water is allowed to penetrate gaps of fibers of the clothes. Then, dirt components attached to the fibers are surrounded with the surfactant and drawn into the cleaning water. The dirt components attached to a hydrophobic group of the surfactant and drawn into the cleaning water are surrounded with surfactant molecules and solubilized, and hence the dirt components do not attach to the fibers again. After end of the cleaning operation, the cleaning water is discarded from the drum, and the city water is newly received as rinse water to execute a rinse operation. In consequence, the fibers are washed with a large amount of water, and the surfaces and inner parts of the fibers are brought into a clean state. Then, the rinse water used in the rinse operation is discarded from the drum in the same manner as in the cleaning water.
According to such a series of cleaning and rinse operations, a large amount of city water is used in the cleaning water and the rinse water and discarded. Therefore, it is demanded that the water for use in the cleaning and rinse operations should be saved to contribute to the environment. Heretofore, for example, a part of the rinse water has been used as the next cleaning water, and the water has been reused to save the water. In this case, the final rinse water for use in a subsequent stage of the rinse operation is once received in a storage tank, and used as the cleaning water in the next cleaning operation.
However, the water used as the cleaning water and the rinse water used in a previous stage of the rinse operation are still discarded, and hence it is difficult to realize remarkable water saving.
On the other hand, a method for removing the surfactant from surfactant-including for-treatment water, and a device are developed. For example, in a surfactant-including waste water treatment device disclosed in Patent Document 1, waste water is mixed with a granular activated carbon, and the surfactant is adsorbed by the activated carbon and removed from the waste water. Then, the waste water from which the surfactant has been removed is discharged to the outside as it is, and the activated carbon in which adsorbed surfactant is concentrated is discarded as the waste activated carbon.
On the other hand, in a surfactant removal device disclosed in Patent Document 2, the surfactant is adsorbed by the activated carbon from the surfactant-including waste water in the same manner as described above, the activated carbon having a deteriorated adsorption capability is subjected to an ozone treatment to desorb and decompose the surfactant, and the activated carbon is regenerated.
[Patent Document 1] Japanese Patent Application Laid-Open No. 5-68965
[Patent Document 2] Japanese Patent Application Laid-Open No. 5-212374
As described above, in the conventional surfactant removal device, activated carbon is used as means for removing the surfactant from the waste water. The adsorption capability of this activated carbon gradually deteriorates owing to the adsorption of the surfactant or the like, and hence a replacement operation with a new activated carbon or the regeneration of the activate carbon is required. In consideration of an impact on the environment, a regeneration treatment of the waste activated carbon which has adsorbed the surfactant is essential, but the regeneration treatment of the activated carbon requires a desorption and decomposing treatment with ozone as disclosed in Patent Document 2. However, the regeneration device of the activated carbon has a complicated mechanism, and has a problem that the activated carbon is consumed by oxidization decomposition.